Goldfish surviving in pond with no care?

My dad works at an elementary school that has a goldfish pond. One of the teachers built it when she worked there a few years ago. After she left (and I think she has been gone for a few years) no one has fed the fish or cleaned the pond. They just left it alone and the goldfish are still alive. I was wondering if anyone would have any idea how they have survived for this long and can they be happy and healthy in that pond? Also, I bought a fish last summer that was supposed to be a koi fish but I think it is a fancy goldfish since it has no whiskers and looks almost exactly like my fantail goldfish. If I had to release one of my goldfish into a pond, would it be alright in the pond I mentioned? Like I said, I don't think I have a koi fish but just in case I do need to find it another home, would it be alright in the school's pond like the other fish? Thanks in advance for any help!!!